#include<stdio.h>
#include<math.h>
int main()
 {
   double r = 0,v = 0;
   scanf("%lf", &r);
   double pai = 3.1415926;
   v = (4.0/3.0)* pai *pow(r,3);
   printf("%.3lf",v);
   return 0;
}
